This invention relates generally to the field of microelectronic devices, and more particularly to a post-in-crown capacitor and method of manufacture.
Electronic equipment such as televisions, telephones, radios, and computers are often constructed using semiconductor components, such as integrated circuits, memory chips, and the like. The semiconductor components are typically constructed from various microelectronic devices fabricated on a semiconductor substrate, such as transistors, capacitors, diodes, resistors, and the like. Each microelectronic device is typically a pattern of conductive, semiconductive, and insulative regions formed on the semiconductor substrate.
A capacitor is one such microelectronic device that is used in a number of applications. Each capacitor has an associated capacitance and a switching speed. The capacitance is indicative of the maximum charge that can be stored in the capacitor; and the switching speed is indicative of the speed that the capacitor can be discharged and recharged. In general, the switching speed of the capacitor decreases the larger the physical size of the capacitor. In contrast, the larger the physical size of the capacitor the greater the capacitance of the capacitor.
A dynamic random access memory (DRAM) device is generally formed from an array of memory cells with each memory cell having a single transistor and a single capacitor. The capacitance of the capacitor used in a memory cell must be greater than a minimum threshold capacitance. The minimum threshold capacitance is needed because the memory cell has no internal amplification and the charge stored in the capacitor is attenuated when the memory cell is accessed. In addition, the stored charge must be greater than the resolution limit of a sensing amplifier that is used to detect the charge stored in the capacitor.
The density and switching speed of the memory cells in a dynamic random access memory device can be increased by decreasing the physical size of the individual capacitors within each memory cell. Increasing the density and switching speed of the memory cells in the dynamic random access memory device increases the computing power and speed of the dynamic random access memory device. However, reducing the size of the capacitor can reduce the capacitance of the capacitor below the minimum threshold capacitance, thereby rendering the memory cell and the dynamic random access memory device inoperable.
Accordingly, a need has arisen for a post-in-crown capacitor and method of fabrication. The present invention provides a post-in-crown capacitor and method of fabrication that substantially eliminates or reduces problems associated with the prior systems and methods.
In accordance with one embodiment of the present invention, a post-in-crown capacitor is provided. The post-in-crown capacitor comprises a crown coupled to a conductive via. A post is disposed within the crown and a capacitor insulation layer is disposed on all surfaces of the post and crown. A capacitor plate layer is then formed outwardly from the capacitor insulation layer.
Important technical advantages of the present invention include providing a post-in-crown capacitor that, for a given capacitance, is physically shorter than many conventional capacitors. Accordingly, the size of the post-in-crown capacitor required to obtain the minimum threshold capacitance for a memory cell is smaller than many conventional capacitors. In addition, the smaller size of the post-in-crown capacitor allows the density of microelectronic devices that are fabricated on a given planar area of the substrate to be increased. In a particular application, the reduced size of the post-in-crown capacitor decreases the size of the memory cell and can, thereby, increase the number of memory cells in a dynamic random access memory. The increased number of memory cells increases the available memory in the dynamic random access memory array. Another technical advantage of the present invention is that the capacitance, for a given physical size, of the post-in-crown capacitor is greater than many conventional capacitors.
Yet another technical advantage of the present invention is that the switching speed of the post-in-crown capacitor is faster than many conventional capacitors. Specifically, the overall height of the post-in-crown capacitor is reduced, which reduces the distance that an electrical charge must travel in order to charge or discharge the post-in-crown capacitor. Accordingly, the switching speed of the memory cell is increased, which increases the computing speed of the dynamic random access memory device.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, description and claims.